Effective rehabilitation of chronic severe aphasia remains an elusive goal. Despite the best efforts of speech therapists, approximately 25% of all patients newly aphasic due to stroke vill be left vith severe communicative deficits. The research proposed is focused upon the extent to which the commnmicative deficits in aphasic patients are specific to the medium of natural language, i.e., the extent to which these deficits can be ameliorated if a different form of commmication is provided. The experiments utilize a computerized visual communication system, C-VIC, which has been specifically designed around the residual strengths of aphasic patients and has been demonstrated to provide a qualitative increase in communicative abilities for some patients vith Broca's and global aphasias. Patients with chronic non-fluent aphasias will be trained in C-VIC and English. A graded set of experiments is proposed to evaluate their comprehension and production of communication in these modalities. The experiments will begin at the single work level, and extend to the analysis of whole sentences and discourse. Because of the pivotal position of verbs in language, particular emphasis will be placed upon the patients' comprehension and production of them as well as of the linguistic rules that govern the relationships between verbs and the other elements in sentences. The goal of these experiments is to determine whether the communicative deficits of aphasic patients cross modalities and thus represent fundamental cognitive deficits in communication or whether some of these deficits are specific to the channel of auditory-verbal language. This information will be valuable, both for the understanding of the cognitive processes subserving language, and for the improved design of speech therapy programs and alternative communication systems for acquired aphasia.